ngk bpr6es plugs loss of power I'm confused

[350war]

Hey guys I just put in a set of ngk's gapped @ .028. It had bosch platinum plus plugs in it. Seems like I lost power. Also now has a pop like a small backfire @ idle. It was running fine before I changed plugs. I'm confused I thought it would run the same if not better with the recomended plugs. Should I change the gap to .032? Any help would be appreciated. Thanks. Plug change was the only thing I did.

 

[Colt4G63 also]

Seems like you should double check your plugs. .028 is the correct gap, maybe one is cracked.

 

[350war]

Checked the plugs pretty good before installing them but I could have missed a small crack I dont know.